Prior application of the same inventor have dealt with a fiber-reinforced composite ring for the controlled release of at least one bioactive agent incorporated in a biocompatible matrix reinforced with absorbable/biodegradable fibers capable of providing the mechanical properties needed for inserting and maintaining the ring in a body cavity for a desired period of time. Such ring system can be used for the intravaginal, intraperitoneal, and subcutaneous delivery of at least one bioactive agent, including those used as contraceptives.
U.S. application Ser. No. 60/482,898 discloses a controlled drug release device comprising a partially or fully absorbable, fiber-reinforced composite ring system comprising an absorbable or non-absorbable matrix, an absorbable, reinforcing fibrous construct and an absorbable coating to provide three modes of controlling the release of bioactive agents and one mode for modulating the mechanical property of the ring in a body cavity during device functional use. For partially absorbable ring systems, the drug release is dependent initially on the diffusion rate of the drug through the matrix and the absorbable coating. As the latter degrades with time, the diffusion through the matrix prevails. Meanwhile, as the absorbable fibrous reinforcing construct undergoes degradation with time, the mechanical strength of the composite ring decreases to provide the desired mechanical strength retention profile. For a fully absorbable composite ring system, the degradation of the matrix offers an additional mode of controlling the release profile as compared with the partially absorbable counterpart. In effect, the invention of U.S. application Ser. No. 60/482,898 deals with a fiber-reinforced composite ring system for the controlled release of at least one bioactive agent comprising a biocompatible matrix reinforced with an absorbable/biodegradable fibrous construct capable of providing the mechanical properties needed for inserting and maintaining said ring in a body cavity for the desired period of time, and wherein the absorbable/biodegradable reinforcing fibers are made primarily from one or more cyclic monomer(s) including glycolide, 1-lactide, .epsilon.-caprolactone, p-dioxanone, and trimethylene carbonate.
For the partially absorbable/biodegradable composite ring controlled drug delivery system of U.S. application Ser. No. 60/482,898, the fiber-reinforced composite ring deals with the controlled release of at least one bioactive agent and comprises a biocompatible matrix reinforced with absorbable/biodegradable fibers capable of providing the mechanical properties needed for inserting and maintaining said ring in a body cavity for the desired period of time, wherein the reinforcing fibers are absorbable/biodegradable and the matrix is non-absorbable/non-biodegradable, wherein the non-absorbable matrix comprising a methacrylate polymer derived from at least one alkyl methacrylate monomer, and wherein the methacrylate polymer is derived from one or more alkyl methacrylate monomer(s) and N-vinyl pyrrolidone. Alternatively, the matrix may comprise a cyclodextrin or cyclodextrin derivative.
Obviously, the partially absorbable/biodegradable composite ring controlled drug delivery system of U.S. application Ser. No. 60/482,898 did not fully address the use of safe matrices such as silicones and polyether urethanes, which are cited in the prior art as carriers of many bioactive agents. Accordingly, this invention addresses the use of non-absorbable/biostable polyether urethane or polysiloxanes as the primary matrix component of the partially absorbable/biodegradable fiber-reinforced composite ring system comprising a drug solubility modifier for the controlled delivery of many bioactive agents including those cited in U.S. application Ser. No. 60/482,898.